The present invention relates to a method of manufacturing a semiconductor device and is, for example, suitably applicable to a method of manufacturing a semiconductor device including a trench type MOSFET.
As one of the MOSFETs (Metal Oxide Semiconductor Field Effect Transistor, MOS type field-effect transistor), there is commonly used a trench type MOSFET including a gate electrode which is embedded inside a trench, via a gate insulating film, formed in a main surface of the semiconductor substrate. Also, when forming a trench gate electrode with high-concentration impurities, there is known a method as follows. That is, first, a silicon film for filling the trench is formed. Then, by applying heat treatment in a state where a film containing impurities is deposited over the silicon film, the impurities are diffused from the film into the silicon film to form the trench gate electrode including the silicon film.
In Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2012-256839), there is disclosed an example in which a silicon oxide film and a poly-silicon film are simultaneously etched using a mixed gas of CH4 and CHF3.
Moreover, in Patent Document 2 (Japanese Unexamined Patent Application Publication No. 2013-140885), there is disclosed an example in which a silicon film is etched using a CH4 gas and an O2 gas.